Plastic Alternatives and 3D Printing

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After plastic was invented, scientists enthusiastically created new materials and technologies to replace traditional natural products with those made from oil or oil by-products. As the world debates the ramifications of unfettered fossil fuel consumption, global climate change, and widespread industrial pollution, scientists and engineers are re-think manufacturing. Plant biologists, in particular, are combining cutting-edge technology with new knowledge of plant biology and biochemistry to go ‘back to the future’ by hunting for next generation natural products to replace those we now make from oil.

Creating Plant-Based Alternatives

The search for plastic alternatives has led many researchers to investigate wood-based substitutes for manufacturing everything from textiles to insulation. Some people are driven by the hunt for sustainability – they want to reduce the reliance on fossil fuels. Others are propelled by financial incentives; they want to be the first out of the gate to create value from bio-based materials and capture new market opportunities. Regardless of their motivation, researchers have made incredible strides in bio-based manufacturing in the past year, and nowhere is that more exciting than in the ‘additive manufacturing’ technology of 3D printing.

Plastics and metals have, until now, dominated additive manufacturing. Although the news is full of 3D printing ‘firsts’, there are myriad technical issues involved with bio-printing, issues that have prevented the technology from being used across a full range of raw materials. A research group at Chalmers University of Technology in Sweden has, however, solved some critical problems with bio-material printing by creating a cellulose hydrogel as the raw printing material. The group also developed a “critical” drying process so the printed piece retained its shape.

Utilizing Renewable Resources

Plants produce an estimated 180 billion tonnes of cellulose every year, making it one of the most abundant organic compounds on earth, and a tempting renewable resource. A plant makes cellulose by linking units of glucose together to form chains, which are then bundled together to form fibers. These fibers form the scaffolding of plant cell walls, giving shape and strength, and acting as a barrier to the outside environment. The researchers at Chalmers University state that “combining the use of cellulose to the fast technological development of 3D printing offers great environmental advantages” because “cellulose is an unlimited renewable commodity that is completely biodegradable, and manufacture using raw material from wood…that would otherwise end up in the atmosphere.”

In Finland, researchers are also developing new bio-material applications, in part to support a national drive towards a bio-economy. Wood has been referred to as ‘Green Gold’ as the country is heavily investing in research for new high-value cellulose-based applications to compliment their traditional pulp and paper industry. The VTT Technical Research Centre of Finland is developing wood fiber-based insulation materials and sprayable insulation foams. The new materials will “enable mass production of high-quality insulation products, which will replace plastic and mineral insulation products made of non-renewable or poorly recyclable raw materials.” The Thermal Insulation Manufacturers and Suppliers Association (TIMSA) states that, of the various insulation materials, polyurethane foams have the highest, and cellulose insulation materials the lowest, environmental impact. Environmental sustainability aside, plastic-based insulation contains hazardous components that have health implications for insulation workers. No such health hazards exist for workers installing cellulose insulation.

Other Applications

In addition to new materials and products, new types of manufacturing equipment and processes are also being developed and tested. Advances in manufacturing technologies often owe their success to research studies conducted in far-removed labs. At Purdue University in Indiana, researchers have discovered the structure of the enzyme that makes cellulose, a finding that scientists hope could lead to easier ways of breaking down plant materials. Scientists at the University of Melbourne are working hard to identify the nanostructure of cellulose, which could pave the way for growing more disease resistant varieties of wood, which could increase the sustainability of wood-based industries.

In experiments, the scientists at Chalmers University also mixed carbon nanotubes into cellulose gel, and then mixed conductive and non-conductive gels together to produce three-dimensional circuits. “Potential applications range from sensors integrated with packaging, to textiles that convert body heat to electricity, and wound dressings that can communicate with healthcare workers.” Back to the future, indeed!